'attribute': attribute has undefined behavior on a nested UDT
Attributes that apply to nested UDTs (user-defined type, which could be a typedef, union, or struct) may be ignored.
The following code shows how this warning would be generated:
// compile with cl /c [emitidl, module(name="xx")]; struct IUnknown {}; [custom, uuid("00000000-0000-0000-0000-000000000002")] __interface IMy { }; [coclass, appobject, uuid("00000000-0000-0000-0000-000000000001")] class CMy : public IMy { [export, v1_enum] typedef enum myEnum { k3_1 = 1, k3_2 = 2 } myEnumv; };